Practical Techniques for Selecting Transient Suppressing Diodes

Practical Techniques for Selecting Transient Suppressing Diodes

Transient Suppressing Diodes (TVS Transient-voltage-suppression diode for short) is a high-efficient protective device in the form of diode. When the two poles of a TVS diode are subjected to reverse transient high-energy shocks, it can convert the high impedance between the two poles into low impedance at a speed of 10 to the negative 12th power second, absorbing up to several kilowatts of surge power, and clamping the voltage between the two poles at a predetermined value, effectively protecting precision components in electronic circuits from damage caused by various surge pulses. Many friends have little understanding of transient suppression diodes, and they may not even know how to choose them. Today, I will share with you practical tips for selecting transient suppression diodes!

Tips for selecting transient suppression diodes:

1. Determine the maximum DC or continuous operating voltage of the protected circuit, the rated standard voltage of the circuit, and the "high end" tolerance.

2. The Transient Suppressing Diodes rated reverse turn off VWM should be greater than or equal to the maximum operating voltage of the protected circuit. If the selected VWM is too low, the device may enter avalanche or the normal operation of the circuit may be affected by excessive reverse leakage current. Serial connection for voltage sharing and parallel connection for current sharing.

3. The maximum clamping voltage VC of TVS should be less than the damage voltage of the protected circuit.

4. Within the specified pulse duration, the maximum peak pulse power consumption PM of TVS must be greater than the possible peak Pulsed power in the protected circuit. After determining the maximum clamping voltage, its peak pulse current should be greater than the transient surge current.

5. For the protection of data interface circuits, attention must also be paid to selecting TVS devices with appropriate capacitance C.

6. Choose the polarity and packaging structure of TVS according to its purpose. The selection of bipolar TVS for AC circuits is more reasonable; Choosing TVS array for multi line protection is more advantageous.

7. Temperature considerations. The transient voltage suppressor can operate between -55~+150 ℃. If Transient Suppressing Diodes needs to operate at a changing temperature, its reverse leakage current ID increases with increasing; The power consumption decreases with the increase of Transient Suppressing Diodes junction temperature, from+25 ℃ to+175 ℃, approximately linearly decreasing by 50%. The rain breakdown voltage VBR increases with a certain coefficient as the temperature increases. Therefore, it is necessary to consult relevant product information and consider the impact of temperature changes on its characteristics.